FLORIDA GEOLOGICAL SURVEY
The 2nd moment measure (standard where the moment measures are defined in deviation) tells us about the dispersion about Table 4. The 3rd moment measure the 1st moment measure, but leaves no (skewness) of equation (3) has a value of 20 insight as to how the distribution departs added to it in order to assure that positive either symmetrically or asymmetrical from values will result. The parameter 0 when the normal bell-shaped frequency curve (or evaluated using S. I. units has units of L-1 from the straight line for the cumulative (dimensionless units result when curve plotted on standard probablity paper). granulometric measures are evaluated in phi Such departure is a characteristic of the tails units). By using seasonal values of 0, that of the distribution about which knowledge is is, 0s for the storm season and 6L for the lull progressively imparted to us by considering season, it may be possible to compile a the 3rd moment measure (skewness), 4th sedimentologic response element parameter moment measure, (kurtosis), and higher that can be incorporated into equation (1). moment measures (Tanner, personal The proper form of the parameter, including communication; Balsillie, 1995). It is, in equation (3), however, requires additional fact, the tails of the distribution which can data, research, and testing. provide a great deal of environmental
information. It has been demonstrated, for Astronomical Ts instance, that there is an inverse relationship
between the kurtosis and the level of surf That mean astronomical tide wave energy expenditure (Silberman, 1979; elevations exhibit cyclic seasonal variability Rizk, 1985; Rizk and Demirpolat, 1986; has long been established (Marmer, 1951; Tanner, 1991, 1992). Tanner (1992) has Swanson, 1974; Harris, 1981) and is reported a correlation between sea level rise included in tide predictions. The U. S. and kurtosis, because the rise component is Department of Commerce (1987a, 1987b) attended by an increase in surf wave energy states, however, that at "... ocean stations expenditure. the seasonal variation is usually less than half a foot." Mariner (1951) notes that
From the preceding discussion, it is seasonal variation in terms of monthly mean apparent that two general cases can be sea level for the U. S. can be as much as identified where wave energy levels either 0.305 m (1 foot; Table 5); some examples exceed stability constraints of the coarsest for the U. S. east, Gulf, and west coasts are fraction of the sedimentologic distribution, or illustrated in Figure 11. Based on the many they do not. For three moment measures years of monthly data, researchers (Marmer, considered to best represent sedimentologic 1951; Harris, 1981) note slight variations in response to the wave energy force element, the seasonal cycle from year-to-year, but storm and lull season responses are listed in also recognize the periodicity in peaks and Table 4. For the two cases (Table 4) only troughs over the years. For much of our the kurtosis persists in providing a response, coast, lower mean sea levels occur during because the 4th moment measure is not the winter months and higher mean sea rendered ineffective to register a change by levels during the fall. Harris (1981) excessive wave energy levels. Therefore, a inspected the record to determine if storm parameter for consideration that more nearly and hurricane occurrence was in any way quantifies sedimentologic response might be responsible for the seasonal change, but given by: found "... no systematic variability". Galvin (1988) reports that seasonal mean sea level
S-20 + Sk) K (3) changes are not completely understood, but
D suggests that there appears to be two primary causes for lower winter mean tide
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